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King Engine Bearings MB5257SI1.25 Main Bearing Set GM OHV Silicon Aluminum - 379 V8

(GMC G2500 1983-95, Yukon 1994-97, K1500 1982-86, 1988-98, C1500 1982-86, 1988-97, K2500 1982-86, 1988-2000, Jimmy 1982-91 + 72 more models)

Part of: King Engine Bearings Main Bearing Set Oversize

Other options in this family: King Engine Bearings MB5835SI0.5 King Engine Bearings MB5557SI0.75 King Engine Bearings MB4102SI0.25 King Engine Bearings MB5280SI0.5 King Engine Bearings MB5770SI0.25

Manufacturer

Picture for manufacturer King Engine Bearings

Part Number

MB5257SI1.25
12 reviews
Sale Price

$85.18

Estimated ship date Monday, November 23

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Fitment guaranteed

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Product Details

The King Engine Bearings MB5257SI1.25 is a complete main bearing set designed for General Motors 379 cubic inch V8 OHV engines. Manufactured using King's bi-metal silicon aluminum construction, this bearing set delivers reliable performance and durability for medium-duty applications.

Material & Construction:

  • Bi-Metal Silicon Aluminum — aluminum-based alloy strengthened with 2.5–3% silicon content
  • Optimized for medium load engines and nodular cast iron crankshafts
  • Silicon aluminum provides excellent conformability and fatigue resistance
  • 1.25 undersize (OS 1.25) to accommodate reground or worn crankshaft journals

Key Features:

  • Complete main bearing set for GM 379 V8 OHV applications
  • Precision engineered to King's tight manufacturing tolerances
  • Designed to maintain proper oil film for reduced friction and wear
  • Undersize designation ensures proper fitment on machined crankshafts

King Engine Bearings is a globally recognized manufacturer known for producing high-precision engine bearings used in OEM and performance applications worldwide. The MB5257SI1.25 is an ideal replacement choice for engine rebuilders working on General Motors 379 V8 OHV powerplants requiring an undersize main bearing set.

Products specifications

Fits

GMC G2500 1983-95, Yukon 1994-97, K1500 1982-86, 1988-98, C1500 1982-86, 1988-97, K2500 1982-86, 1988-2000, Jimmy 1982-91, Savana 2500 1996-2002, Savana 3500 1996-2002, C3500 1982-86, 1988-2000, K2500 Suburban 1982-86, 1994-99 + 68 more models

Undersize

1.25

Material

bimetal (aluminum silicon base)

Flange Oversize

FL ON MAX

Great so far.

So far, so good. Right part, fit perfect. What's else can a man ask?

My only complaint is that the site couldn't identify the size wheel center caps I needed by vehicle type. I had to measure the center hole on my wheels, lucky I'm a tool junky.

No issues - a bit slow, but otherwise OK

very happy

Great product lines good prices

Second time customer of Autoplicity: Ordered Husky Liners Weatherbeater Floor mats for a 2012 Toyota Tundra, Called in this morning to verify availability, call answered on second ring, great service placed the order immediately. Haven't even received the product yet but the service has been so outstanding had to let everyone know this company is for real. Best pricing online, wont buy products anywhere else.<br><br>Justin Myers

Very good so far.

VERY EASY WITH AMAZON SIGN IN

Great Price and questions were answered by a real person on the phone, who had specific knowledge of this product, unlike a local dealer! Thanks!

Easy and quick

very fast and easy.

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